A projector is used widely in a presentation of a conference etc., because the projector can project and display enlarged pictures. The projector and a picture output apparatus which have been generally used is in a one-to-one relationship. However, recently, a plurality of projectors is often used and managed via a network in companies, schools etc. where projectors are installed in a plurality of rooms.
Parts necessary for periodic maintenance such as lamps, air filters etc. are used in a projector. Therefore, it is convenient for a system manager to manage each projector via a network.
For example, a centralized management method for the projectors of the network system which includes projectors is disclosed in Japanese Patent Laid-Open No. 2002-287242 (hereinafter referred to Document 1).
In the method described in Document 1, providing a projector with a hub for a network makes it easy to structure a network system. After structuring a network system, centralized management of the projectors via the network is possible.
In addition, an apparatus for detecting that a LAN cable is plugged or unplugged from a LAN cable connector, and for detecting removal of devices from a network is disclosed in Japanese Patent Laid-Open No. 2003-122458 (hereinafter referred to Document 2).
The apparatus described in Document 2, when a LAN cable is unplugged from a LAN cable connector, stops supplying power to LAN interface unit. Thereby, it provides an apparatus capable of reducing power consumption.
There is concern over the possibility of theft of the projector, described in Document 1, from the room at times when no one is present, such as, for example, at night.
In the network system described in Document 1, the stolen projector will be used again as a network projector, if the stolen projector is connected to a network at other place. In addition, the stolen projector will be used alone, if the stolen projector is not connected to a network. Therefore, security measures to prevent theft are not considered necessary.
In the invention described in Document 2, whether a LAN cable is plugged or unplugged from a LAN cable connector can only be physically detected. Therefore, even if the invention described in Document 2 is used, there are no effective security measures to prevent theft.
Furthermore, it is considered that USB memory etc. is used as a key for security. In this case, management tasks are complicated for a manager, because it is necessary to manage a projector and a USB memory separately.